[Cryptography] N. Korean radio broadcasts string of random numbers

[Henry Baker]

At 12:13 PM 9/4/2016, Tom Mitchell wrote:
>If this is a clandestine transmitter by an agent it is interesting at other levels.
>
>With modern tools voice or CW can transmit global signals with power
>from a lunch box and a long tuned wire antenna.  Timers can make it quiet
>(power off) except on a schedule.  Spread spectrum keyed by a number
>code from the mother ship might be near impossible to locate for
>a return message.

Ultra wideband (aka pulse position modulation) can be even more difficult
to find -- especially if the geographic position of the emitters can be
dynamically and randomly varied.  Synchronization of such geographically
dispersed transmitters has become trivial due to the availability of GPS.

Of course, multiple spreading technologies can be combined.

https://en.wikipedia.org/wiki/Ultra-wideband